A recent study published in Molecular Biology and Evolution reports that Italian bears residing in areas near villages have evolved to become both smaller and notably less aggressive. This research highlights how humans profoundly influence ecosystems and biodiversity, with activities like habitat change and overuse shifting selective pressures and affecting how species evolve.
What Does The Study Focus On?
The study focuses on the endangered Apennine brown bear (Ursus arctos marsicanus). This small population lives exclusively in Central Italy. For centuries, these bears have shared landscapes with human communities.
Previous research shows that Apennine brown bears diverged from other European brown bears 2,000–3,000 years ago. They have remained genetically isolated since the Roman era. According to lead author Andrea Benazzo, forest clearance played a key role for this isolation. Agricultural expansion and rising human population density further accelerated the decline.
Evolutionary Changes and Genomic Findings
Today, Apennine brown bears differ markedly from other brown bear populations worldwide. They have smaller bodies and distinct head and facial features. They also display less aggressive behaviour.
Researchers examined recent evolutionary changes shaped by human pressure. They produced a high-quality, chromosome-level reference genome for the population. The team re-sequenced whole genomes from several individuals. They then compared these genomes with bears from Slovakia and North America.
As expected, the Apennine bears show low genomic diversity and high inbreeding. However, co-author Giulia Fabbri highlighted a striking result. The genomes contain selective signatures linked to reduced aggressiveness. The data suggest humans removed more aggressive individuals over generations. This pressure likely favoured behaviour-related genetic variants.
Implications for Coexistence and Conservation
The study also shows a complex outcome of human encroachment. Human activity caused population decline and genomic erosion. These effects increased the risk of extinction. At the same time, human pressure unintentionally shaped traits that reduced conflict.
Researcher Giorgio Bertorelle emphasized the broader message that human–wildlife interactions often threaten survival. Yet, they can also drive adaptive changes that reduce conflict. For conservation planning, this is critical. Severely impacted populations may carry valuable genetic variants. Conservation strategies should protect these traits rather than dilute them through restocking.
The Apennine brown bear evolved through selective human pressure. Human actions reduced their population size also the genetic diversity. However, repeated removal of aggressive individuals favoured calmer traits. These changes helped the bears persist alongside challenging human neighbours.
Reference Source
Coexisting with humans: genomic and behavioural consequences in a small and isolated bear population, Molecular Biology and Evolution (2025). DOI: 10.1093/molbev/msaf292
